52 THE BKOWX-TAIL MOTH. 



Natural Enemies. 

 One reason why the brown-tail moth is so very injurious 

 in Massachusetts is found in the lack of the parasitic ene- 

 mies Avhich liold the insect more or less in check in its 

 oriij^inal home. As 3^et our native parasites have not ada})ted 

 themselves to this new caterpillar, and, freed from the 

 checks that control it at home, it here causes a greater and 

 longer-continued damage than is common in Europe. Of 

 the Hymenopterous parasites conmion to caterpillars of this 

 class, Pimjjla (emdconiis Cr. and ]%<mgenes hehe Cr. have 

 been bred in some numbers from the cocoons. The greatest 

 natural aid in destro^nng the brown-tail moth seems to be 

 the tinv parasite DbjlocUh omnivora Walk. Large num- 

 bers breed in a single pupa, and, emerging early in the 

 season, attack other larvjv and pupaj, and thus prevent their 

 development into moths. From a single pupa 158 DiglocJm 

 were obtained in July, 1898, while from a mass of about 

 four (juarts of cocoons over three thousand of these para- 

 sites emerged during the same month. Of the dipterous 

 parasites, the only one determined is EtipJiorocera clari- 

 pennia Macq. So far as we have observed, the caterpillar 

 is only slightly attacked by parasites of this class. 



Tlic number of })redaceous bugs which assemble on trees 

 infested with the brown-tail moth early in the s})ring is 

 (juite remarkable. These bugs, hibernating in sheltered 

 localities, eagerly seek food in the first warm days of 

 spring. The brown-tail moth caterpillar is the largest 

 insect of its kind which is at all abundant early in the 

 season, and the })redaceous bugs readily adapt themselves 

 to it. The result is irri'atly to the advantage of the bugs 

 and to the fanner. Ma}' 1, iSHil, witli the therniometcir in 

 the shade at ItO'^ F., six trees infested with the ])rown-tail 

 moth were exaniiiu'd, with the result that the following 

 nninlx'r of predaceous inseits were found feeding U})on the 

 small etiterpillars : 118 Podisus serierentris, I3G Podisiis 

 phtridiis, 2 Mili/a.s ciiuiu.s, 1 LiotrapiH InuneraUs, 1 wasp, 

 Pnlish-s jiallipes; in other words, on the six infested trees 

 tiiere were 152 predaceous bugs at work destroying the 



